1. Field of the Invention
Aspects of the present invention generally relate to a three-dimensional (3D) scanner that measures the 3D shape of a target object, which is targeted for scan, in a non-contact manner.
2. Description of the Related Art
3D scanners construct 3D models by combining results that are obtained by optically measuring a target object from a plurality of directions. However, in a case where the surface of a target object has no features, the positions or angles for combining results obtained by measuring the target object cannot be specified, so that it is difficult to construct an accurate 3D model. Therefore, a scheme capable of specifying the position or orientation of a target object is ordinarily used together with a 3D scanner to calculate the combining position or angle. In this regard, in order to accurately and efficiently construct a 3D model, it is important for a target object to be located in an accurate position and to be measured from necessary directions.
Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2007-508557 discusses a method in which, in order to accurately specify the position of a target object, the target object is located on a scan template member, which has a known two-dimensional plate, and is then scanned. This method enables accurately grasping the position of the target object based on the positional relationship between images of the two-dimensional plate and the target object that are included in a video image captured by a camera, thus enhancing the precision of construction of a 3D model. Japanese Patent Application Laid-Open No. 2002-74347 discusses a technique of, with the use of a handy 3D scanner, instructing the user as to in which direction to move the 3D scanner.
Stationary 3D scanners can perform accurate 3D scan accordingly as the user appropriately locates, moves, and rotates a target object. If an index used for the user to uniquely grasp an optimum scan position or orientation of the target object is present on a stage on which to locate the target object during scan, the user can promptly locate the target object in an appropriate position. In conventional methods, an instruction screen used for providing an instruction on the position or orientation of a target object is displayed on, for example, the display screen of a personal computer, and the user gropes for an appropriate position according to the instruction screen. This may cause the user to feel stress, thus disturbing prompt 3D scan processing.